Eligible subjects will be randomized to GSK573719/GW642444 125/25mcg, GSK573719 125mcg, GW642444 25mcg, and placebo treatment groups in a 3:3:3:2 ratio such that of the planned 1463 total number of randomized subjects approximately 399 subjects will be randomized to each active treatment group and 266 subjects will be randomized to placebo. All treatments will be administered once-daily in the morning by inhalation using a Novel Dry Powder Inhaler (Novel DPI).